JP2005165200A - Optical device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To seal a case at high airtightness so as to prevent the penetration of humidity while reducing thermal influence to the inside of the case of an optical device. <P>SOLUTION: An optical fiber 3 is fixed in the case 1 through a cylindrical part 4 projected from a hole part 1b formed on the side face of the case 1 to the outside in a state that one end part of the optical fiber 3 is aligned to the optical axis of an optical element 5. The inside of the cylindrical part 4 is sealed by low melting point solder 10. After sealing the cylindrical part 4, a cover member 2 is joined to an aperture part 1a of the case 1 by YAG laser welding. Since the cylindrical part 4 is arranged on a position separated from the joint part (outer edge of the aperture part 1a) by welding up to the outside of a range in which thermal energy by laser welding is transmitted, laser welding is not influenced by the existence of the cylindrical part 4. Since heating for sealing the cylindrical part 4 by the low melting point solder 10 is performed in the cylindrical part 4 on the outside of the case 1 and heat for laser welding is locally applied, the influence of heat to adhesive 9 or the like in the case 1 is small. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical device and a manufacturing method thereof, and more particularly to a package sealing structure thereof.

  2. Description of the Related Art Conventionally, optical devices using optical fibers have been widely used in, for example, the optical communication field, and various optical devices such as an optical switch for switching an optical path as an information transmission path and an optical attenuator for attenuating a beam. Is used. In such an optical device, in particular, an optical element optically connected to the optical fiber may cause functional deterioration or failure due to moisture. Therefore, a package structure in which an optical element is accommodated in a housing is widely used. By sealing such a package structure as tightly as possible, the optical element is protected from external moisture, condensation is prevented, and the stability and reliability of the characteristics of the optical device are enhanced.

  As a conventional hermetic sealing method for a package structure of an optical device, for example, in FIG. 5 of Patent Document 1, a concave portion for introducing an optical fiber is provided at a joint portion of a case with a lid member, and a metallized optical fiber is provided. Is described in which the case and the lid member are soldered by placing them in the recess. FIG. 6 of Patent Document 1 shows a method of hermetic sealing using a low-melting glass instead of solder with the same configuration as FIG. 5, and FIG. 7 of Patent Document 1 shows the same configuration as FIG. Describes a method of hermetic sealing using a resin instead of solder.

  An optical device having a package structure is fixed in the case with an adhesive or the like in a state where the end of the optical fiber and the optical element are aligned with each other, and then the case and the lid member are fixed and sealed. . In the method shown in FIGS. 5 and 6 of Patent Document 1, the temperature of the entire package is raised when the lid member is sealed with solder or low-melting glass. For example, it is necessary to heat to hundreds of degrees for sealing with low melting point solder and to about 450 degrees for sealing with low melting point glass. At this time, the adhesive fixing the optical element inside the package may be melted or damaged, causing a relative positional shift between the optical fiber and the optical element. For example, epoxy adhesives and ultraviolet curable adhesives may be damaged when the temperature rises to near 100 ° C. As a result, if the optical axes of the optical fiber and the optical element are shifted, the function as an optical device cannot be achieved. Usually, since it is impossible to correct the relative position of the optical fiber and the optical device after the case and the lid member are fixed, the optical device becomes a defective product that cannot be used unless it is disassembled and remade.

  In the method shown in FIG. 7 of Patent Document 1, since it is not necessary to use a very high temperature at the time of sealing with resin, there is a possibility that the optical axis of the optical fiber and the optical element are displaced due to melting or breakage of the adhesive. Is low. However, since the hermetic sealing level of the resin is lower than that of metal or glass, when it is exposed to severe environmental conditions such as high temperature and high humidity for a long time, moisture enters the package little by little through the resin, Thereafter, when the temperature is lowered, condensation occurs in the optical element, which may cause deterioration of characteristics as an optical device and a decrease in lifetime.

  On the other hand, Patent Document 2 is provided with a cylindrical portion that protrudes outward from the side wall of the casing (case), and the optical fiber passes through the cylindrical portion and passes from the inside of the case to the outside. A protruding configuration is disclosed. In this configuration, the sealing of the cylindrical portion that is the introduction portion of the optical fiber and the joining of the case and the lid member are performed separately. Then, the metallized optical fiber can be soldered in the cylindrical portion. In this case, since the solder is heated in the cylindrical portion away from the inside of the case, the heat is not transmitted so much to the adhesive that fixes the optical element located at the central portion in the case. Thus, in patent document 2, the thermal influence to the inside of a case of sealing of the optical fiber in a cylindrical part is reduced. However, Patent Document 2 does not specifically describe a method for joining the case and the lid member, and does not disclose a structure for completely sealing the entire package. Patent Document 2 does not take into consideration whether the case and the lid member can be sealed with high confidentiality or the possibility of thermal influence on the inside of the case when the case and the lid member are joined.

On the other hand, as a lid member sealing method, Patent Document 3 discloses a method in which a case and a lid member are joined and sealed by resistance welding such as seam welding.
Japanese Patent No. 2943760 (FIGS. 5-7) Japanese Patent Laid-Open No. 7-281061 (FIG. 2) Japanese Patent No. 2616668 (FIGS. 1-4) "A Consideration on Crack Prevention in YAG Laser Welding" Jun Yokoyama, Takashi Shibuya, Kazuhide Okawara, Yuichi Oda (NEC Corporation Optical Cable Communications Development Division) Proc. Page, Paper No. Published by The Institute of Electronics, Information and Communication Engineers

  As an example of resistance welding for joining the case of the optical device and the lid member, so-called can seal welding, which is mainly used for hermetic sealing of ICs, crystal resonators and the like, can be cited. As schematically shown in FIG. 9, the can seal welding is performed by joining an electrode 104 covering the outer shape of the cap 102 and the stem 103 in order to join the cap 102 and the stem 103 constituting the package incorporating the element 101. In this method, the joint is sandwiched between the lower electrodes 105 and a voltage is applied to the electrodes 104 and 105 for welding. When this can seal welding is used for joining the case of the optical device and the lid member, an electrode adapted to the outer shape of the case is required. Therefore, in an optical device that is produced in a small quantity and a variety of products, it is necessary to design and manufacture an electrode for each type of optical device, which causes an increase in manufacturing cost. In addition, since the optical device is generally larger in size than an IC or a crystal resonator, a relatively long distance is welded by a single energization of the electrode. Therefore, there is a problem that the welding result is not stable and airtightness is liable to occur.

  Another example of resistance welding is so-called parallel seam welding. In the case of parallel seam welding, as schematically shown in FIG. 10, a pair of roller electrodes 106 moves while rotating along the outer edge of the lid member 108 to be joined to the case 107 to perform welding. However, when the package shape of the optical device is complicated, particularly when the concave portion for locking the ferrule or the like by the clip-shaped fastening member is provided on the package surface, the optical device package is configured. It is difficult to roll the roller electrode 106 along the outer edge of the lid member 108, and there is a possibility that sufficient bonding may not be performed at a portion where the roller electrode 106 cannot be rolled and moved in contact with the surface of the lid member 108.

  Therefore, an object of the present invention is to seal the optical fiber introduction part and the case and the lid member separately, and to seal the optical fiber introduction part at a position away from the inside of the case. It is an object of the present invention to provide an optical device and a method for manufacturing the same that can reduce the thermal influence of the device, can be firmly sealed even if the package shape is complex, and can prevent moisture from entering the case.

  An optical device according to the present invention includes a hollow case having at least one opening, a cylindrical portion protruding outside from a hole provided in a side surface of the case, and the cylindrical portion and the hole. Extending from the inside of the case to the outside, and joined to the case so as to close the opening by laser welding and an optical fiber fixed in the cylindrical portion by a low melting point solder that seals the cylindrical portion And a lid member.

  In this configuration, sealing of the cylindrical portion and joining of the case and the lid member are performed separately, so that the thermal influence on the inside of the case is suppressed. There is no end position shift or optical axis shift. Moreover, the package comprised from a case and a cover member is sealed favorably.

  It is preferable that the cylindrical portion is separated from the outer edge of the opening of the case to at least the outside of the range where thermal energy is transmitted during laser welding for joining the lid member to the case. Moreover, it is preferable that the cylindrical part is separated from the outer edge of the opening part of the case by a distance longer than at least the penetration depth of the laser at the time of laser welding for joining the lid member to the case. According to such a configuration, at the time of laser welding, uniform welding can be performed under substantially the same conditions at the periphery of the cylindrical portion and other portions, and the sealing reliability and stability are high.

  When laser welding is YAG (Yttrium-Aluminum-Garnet) laser welding, it can be easily performed and good welding can be performed.

  Furthermore, the optical device of the present invention has an optical element disposed in the case so that the optical axis coincides with the optical fiber.

  The lid member and the cylindrical portion are preferably made of Kovar or 42 nickel-iron. The case is preferably made of any one of Kovar, 42 nickel-iron, and a ceramic material. Since Kovar and 42 nickel-iron have a low coefficient of thermal expansion, there is little risk of stress being applied to the fixed portion of the optical fiber or optical element due to thermal expansion or contraction when the temperature changes, causing the optical axis to shift or break.

  When the portion of the optical fiber sealed with the low melting point solder is subjected to metallization with nickel and gold with the coating removed, the fixing with the low melting point solder can be performed satisfactorily. When the thickness of the nickel layer by the metallization treatment of the optical fiber is 1 μm or less and the thickness of the gold layer is 0.2 μm or less, a decrease in tensile strength due to the metallization layer being too thick can be suppressed. If the length of the portion of the optical fiber that has been metallized with the coating removed is 2 mm to 5 mm, the arrangement of the optical fiber is less likely to be disturbed and sufficient sealing is achieved with a low melting point solder. An effect is obtained.

  In addition, the metallization process is performed only on a part of the optical fiber where the coating is removed, and the part where the coating is removed and the metallization process is not performed. It is also possible to adopt a configuration in which a part on the tip side is covered with a protective member.

  When a nickel plating layer having a thickness of 1 μm to 5 μm is formed on the case and the cylindrical portion, the corrosion resistance is improved. Further, when a gold plating layer having a thickness of 0.05 μm to 1 μm is formed on at least the inner surface of the cylindrical portion, the solder wettability is improved and the sealing effect by the low melting point solder is improved.

  An optical device manufacturing method according to the present invention includes an optical fiber in a hollow case having at least one opening, a hole provided in a side surface, and a cylindrical part protruding outside from the hole. A step of passing through the tubular portion and the hole so as to extend from the inside of the case to the outside, a step of sealing the tubular portion with a low melting point solder and fixing the optical fiber in the tubular portion, And a step of joining the lid member so as to close the opening in the case by laser welding after sealing the cylindrical portion.

  If the cylindrical part is sealed after the lid member is joined to the case, the air in the case expands and contracts when the cylindrical part is heated or cooled, so that a vent hole is formed in the molten low melting point solder. There is a possibility that it is formed and solidifies as it is, or the low melting point solder in a molten state is drawn into the center of the case. However, according to the method of the present invention described above, since the cylindrical portion is sealed with the low melting point solder before the lid member is joined to the case, such a problem is prevented.

  Sealing with low melting point solder is performed by locally heating the cylindrical part protruding outward from the case, and joining of the case and the lid member by laser welding is performed locally at the part to be joined. Since it is performed by heating and melting, the temperature of the entire case does not rise excessively, and the adhesive fixing the optical element and optical fiber in the case is damaged by heat and the optical axis shifts. There is no.

  A step of attaching the cylindrical portion to the side surface of the case may be included before the step of arranging the optical fiber. You may attach a cylindrical part to the side surface of a case by brazing.

  The method may further include a step of arranging the optical element in the case and a step of aligning the optical axes of the optical element and the end of the optical fiber and relatively fixing them. The optical axis alignment between the optical element and the end of the optical fiber may be performed inside the case or outside the case.

  It is preferable to further include a step of removing the coating in advance on the portion of the optical fiber that is sealed with the low melting point solder and then performing a metallization treatment with nickel and gold. It is preferable to form a nickel layer having a thickness of 1 μm or less and a gold layer having a thickness of 0.2 μm or less in a step of metallizing the optical fiber. In the step of applying metallization to the optical fiber, it is preferable to apply metallization to a length of 2 mm to 5 mm. Further, in the step of performing the metallization process on the optical fiber, the metallization process is performed only on a part of the portion where the coating is removed, and the metallization process is performed on the part where the coating is removed and the metallization process is not performed. It is also possible to include a step of covering a part on the front end side with respect to the portion where the is provided by a protective member.

  It is preferable to further include a nickel plating step of forming a nickel plating layer having a thickness of 1 μm to 5 μm on the case and the cylindrical portion. It is preferable to further include a gold plating step of forming a gold plating layer having a thickness of 0.05 μm to 1 μm on at least the inner surface of the cylindrical portion.

  According to the present invention, a package mainly composed of a case and a lid member is formed by sealing a cylindrical portion through which an optical fiber passes with a low melting point solder and joining the case and the lid member by laser welding. Sealed, high airtightness level is ensured, and internal dew condensation does not occur to deteriorate the characteristics or shorten the service life.

  Sealing of the cylindrical portion through which the optical fiber passes is performed by heating only the low melting point solder in the cylindrical portion protruding outward from the case, and the case and the lid member are bonded only to the bonding portion. This is done by locally heated laser welding. Therefore, the heat transmitted to the optical element in the case and the adhesive that fixes the optical element is small, and there is no possibility of causing displacement or damage.

  The lid member and the case can be joined by performing laser welding by relatively moving the laser irradiation position and the case and lid member to be joined. Therefore, even if the shape of the case and the lid member is complicated, they can be easily joined, and a constant sealing can be performed regardless of the size. As a result, even when manufacturing a small amount of various types of optical devices, it is not necessary to change the design and configuration of the apparatus for each type, and the production cost can be kept low.

  In particular, when the cylindrical portion is sealed with a low melting point solder prior to joining the lid member to the case, the air in the case expands and contracts during heating and cooling of the cylindrical portion, and the molten state is reduced. There is no risk of damage such as vent holes in the melting point solder.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The optical device of the present invention shown in FIG. 1 has a package structure mainly composed of a case 1 and a lid member 2. The case 1 is a hollow casing, and one surface (the upper surface in FIG. 1B) is an opening 1a. Further, a hole 1b is provided on the side surface, and a cylindrical portion 4 that is an introduction portion of the optical fiber 3 is further provided. The cylindrical portion 4 is provided near the middle of the side surface, at a position sufficiently away from at least the outer edge of the opening 1a, and protrudes outward. The tubular portion 4 is covered with a rubber hood 6. The lid member 2 is joined by YAG laser welding so as to close the opening 1a of the case. The lid member 2 is made of a metal material, and the case 1 is mainly made of a metal material or a ceramic material.

  However, even when the case 1 is mainly made of a ceramic material, the cylindrical portion 4 is made of a metal material, and a sealing frame made of a metal material is formed on the joint surface with the lid member 2, that is, the outer edge of the opening 1a. (Not shown) is brazed. The cylindrical part 4 is airtightly joined to the case 1 by brazing. In addition, the metal material may cause the optical axis to be displaced or the optical fiber 3 to be broken due to stress applied to the fixed portion of the optical fiber 3 or the optical element 5 due to thermal expansion or contraction of the package when the ambient temperature changes. In order to prevent this, Kovar or 42 nickel-iron having a low coefficient of thermal expansion is preferable.

  An optical element 5 such as a light emitting element, a light receiving element, a lens, or a mirror is disposed in a package mainly composed of a case 1 and a lid member 2, and one end of the optical element 5 and the optical fiber 3 has an optical axis. It is fixed with an adhesive 9 or the like in a matched state. The optical element 5 is mounted on the support member 7 and is driven by a drive unit 8 fixed to the support member 7. As described above, one end portion of the optical fiber 3 is aligned and fixed in the case 1 with the optical element 5, and the other end portion passes through the cylindrical portion 4 and extends to the outside of the case 1. It can be connected to other optical devices.

  The cylindrical portion 4 is provided with a solder injection port 4a and an adhesive injection port 4b. Then, the inside of the cylindrical portion 4 is sealed with a low melting point solder 10 (for example, tin-bismuth alloy solder or tin-indium alloy solder) injected from the solder injection port 4a, and adhesion injected from the adhesive injection port 4b. The optical fiber 3 is fixed in the cylindrical portion 4 with an agent 11 (for example, an epoxy-based adhesive or a silicon-based adhesive).

  The portion 3a of the optical fiber 3 sealed with the low-melting-point solder 10 in the cylindrical portion 4, that is, the portion around the solder injection port 4a is removed by coating to expose the core wire (bare optical fiber). Metallized with gold. Although not shown, it has been experimentally known that if the metallized layer of the optical fiber 3 is too thick, the tensile strength of the optical fiber 3 tends to be weak. Therefore, the nickel layer has a thickness of 1 μm or less and the gold layer has a thickness of 0.2 μm or less. It is desirable to make it small.

  As described above, the optical fiber 3 is partially coated and at least a portion of the cylindrical portion 4 facing the solder injection port 4a is coated and metallized. On the inner side of the case 1 relative to the metallized portion 3a that has been stripped, there is a portion that remains without being stripped. This is to prevent the molten low melting point solder 10 from flowing through the optical fiber 3 to the vicinity of the optical element 5. Further, when the optical fiber 3 is a multi-core optical fiber, it is difficult to align the optical fiber 3 when the coating is removed, and the arrangement is disordered in the cylindrical portion 4 as shown in FIG. There is a possibility that the low melting point solder 10 cannot always be stably filled and the unfilled portion 16 is generated. Therefore, the covering portion is left on the end side (inside the case 1) from the metallized portion 3a, and the arrangement of the optical fibers 3 is disturbed in the cylindrical portion 4 as shown in FIG. And can be sealed with the low melting point solder 10. However, the end portion connected to the optical element 5 in the case 1 is stripped. Considering the case of a multi-core optical fiber, the shorter the portion 3a that has been coated and metallized is shorter, the arrangement of the optical fiber 3 is less likely to be disturbed. In order to obtain a sealing effect, the length is desirably about 2 to 5 mm.

  In this way, the coating portions and the coating removal portions of the optical fiber 3 are not provided alternately. As shown in FIGS. 3 and 4, the optical fiber 3 is positioned in the case 1 from the portion corresponding to the solder injection port 4a. It is also possible to remove the coating up to the end to be covered and then cover with a protective member such as the substrate 17 or the ferrule 18 on which the V groove 17a is formed, leaving the solder sealing portion 3a of about 2 to 5 mm.

  The inside of the cylindrical part 4 is not only sealed by the low melting point solder 10 but also fixed by the adhesive 11 because the metallized part of the optical fiber 3 having a length of about 2 to 5 mm is fixed by soldering. This is because the adhesive 11 may be used to further increase the fixing strength of the optical fiber 3 because there is a possibility that sufficient strength against tension or the like may not be obtained.

  As described above, the inside of the cylindrical portion 4 which is the introduction portion of the optical fiber 3 is sealed with the low melting point solder 10, while the opening 1 a of the case 1 is closed with the lid member 2. The case 1 and the lid member 2 are joined by YAG laser welding.

  Although not shown, the case 1 and the cylindrical portion 4 that are brazed and joined are preferably plated with nickel of about 1 to 5 μm as a whole in order to improve corrosion resistance. Further, at least the inner surface of the cylindrical portion 4 is preferably plated with gold of about 0.05 to 1 μm after nickel plating in order to prevent nickel plating oxidation and improve solder wettability. However, when gold plating is performed on the inner surface of the cylindrical portion 4, it is not preferable that the periphery of the outer edge of the opening 1 a joined to the case 1, particularly the lid member 2, be simultaneously gold plated. The reason is as follows. The melting point of gold is 1,060 ° C., and the melting points of Kovar and 42 nickel-iron, which are materials used as the base of the case 1 and the lid member 2, are 1,450 ° C., and the melting points of the two are greatly different. This tends to cause cracks when performing YAG laser welding. This is disclosed in Non-Patent Document 1, and one factor of cracks is that gold having a low melting point contracts due to heat and changes in volume. If gold is contained around the welded portion, cracks may occur and airtightness may occur. Therefore, the case 1 excluding the cylindrical portion 4 is formed with only a 1 to 5 μm nickel plating layer for improving the corrosion resistance. The melting point of nickel is 1,455 ° C. and does not cause cracks. The lid member 2 is not plated or has only a 1 to 5 μm nickel plating layer for improving corrosion resistance. Further, the gold plating layer of the cylindrical portion 4 is subjected to gold plating without masking or the like for simplification of the welding process, and even if gold is mixed around the welded portion of the case 1, the amount thereof is made as small as possible. Therefore, it is formed to be 1 μm or less as described above.

  The fixing position of the cylindrical portion 4 serving as the optical fiber introducing portion to the side surface of the case 1 is sufficiently separated from the joint portion between the case 1 and the lid member 2. This will be described below.

  Laser welding using a YAG laser or the like is a method in which heat energy is locally applied to a very narrow range to be melted and welded. However, if the outer edge of the opening 1a of the case 1 to be laser welded and the cylindrical portion 4 are close to each other, the heat energy applied to the outer edge of the opening 1a escapes to the cylindrical portion 4, and the cylindrical portion 4 In the vicinity, there are differences in laser welding conditions compared to other parts. That is, in the part where the thermal energy for laser welding escapes to the cylindrical part 4, the change in the heat capacity is large, and the melting condition during welding changes. This may lead to poor bonding and poor airtightness. Therefore, the cylindrical part 4 is located sufficiently away from the welded joint (outer edge of the opening 1a) so that the thermal energy of the laser for laser welding is not directly transmitted to the cylindrical part 4. preferable. Specifically, it is desirable that the distance D (see FIG. 1B) from the cylindrical portion 4 to the outer edge of the opening 1a is, for example, 0.5 mm or more. In other words, the distance D from the cylindrical portion 4 to the outer edge of the opening 1a is longer than the distance at which thermal energy is transmitted by the laser welding of the present embodiment, and from the depth of penetration of the laser at the time of laser welding of the present embodiment. Is also preferably long.

  Next, a specific method for manufacturing the optical device of this embodiment will be described. Further, the manufacturing method is shown in a flowchart in FIG.

  First, the cylindrical part 4 is fixed to the side surface of the case 1 by brazing (step S1). Specifically, a hole 1b is provided at a predetermined position on the side surface of the case 1 (a position sufficiently away from the outer edge of the opening 1a), and the tubular portion 4 is attached so as to face the hole. The case 1 is made of metal or ceramic, and when made of ceramic, a metal seal frame (not shown) is brazed to the outer edge of the opening 1a. The cylindrical portion 4 is made of metal. In addition, as a metal material which comprises the case 1 and the cylindrical part 4, Kovar and 42 nickel-iron are used.

  Thereafter, nickel plating is applied to the case 1 and the cylindrical portion 4 (step S2). Furthermore, gold plating is applied to at least the inner surface of the cylindrical portion 4 (step S3). When gold plating is performed on the cylindrical portion 4, masking is performed so that gold does not adhere to the case 1.

  A part of the optical fiber 3, at least a part corresponding to the solder injection port 4a at the time of completion, and a coating on the tip part connected to the optical element 5 are removed (step S4). Further, the metallization process using nickel and gold is performed on the portion (bare optical fiber) 3a where the core wire corresponding to the solder injection port 4a is exposed at the completion of the optical fiber 3 (step S5).

  Next, one end of the optical fiber 3 and the optical element 5 are fixed in the case 1 (step S6). As an example, first, one end of the optical fiber 3 outside the case 1 is optically aligned with the optical element 5 fixed to the support member 7 together with the drive unit 8 and fixed to the support member 7 by the adhesive 9. Then, the support member 7 is fixed in the case 1. Then, the other end side of the optical fiber 3 is protruded from the case 1 through the hole 1b and the cylindrical portion 4 to the outside. As another method, first, one end portion of the optical fiber 3 is caused to enter the case 1 through the cylindrical portion 4 from the outside of the case 1. Then, one end of the optical fiber 3 is aligned with the optical element 5 on the support member 7 fixed in the case 1 and fixed on the support member 7 with an adhesive 9. Depending on the type of optical device to be manufactured, various optical elements 5 such as a light emitting element, a light receiving element, a lens, and a mirror are used, and a drive unit 8 corresponding to the optical element 5 is used. However, the support member 7 and the drive unit 8 may not be present, and the optical element 5 may be directly fixed to the inner surface of the case 1.

  Next, the cylindrical part 4 which is an optical fiber introduction part is sealed with the low melting point solder 10 (step S7). That is, the low melting point solder 10 is injected from the solder injection port 4a of the cylindrical portion 4 through which the optical fiber 3 is inserted and solidified. At this time, the cylindrical portion 4 is locally heated to a melting point of the low melting point solder 10 (for example, 139 ° C. in the case of tin-bismuth eutectic solder, 118 ° C. in the case of tin-indium eutectic solder) or more. In a heated state, the molten low melting point solder 10 may be injected from the solder injection port 4 a, or the paste-like low melting point solder 10 is injected from the solder injection port 4 a and heated inside the cylindrical portion 4. And may be melted. Thereafter, the cylindrical portion 4 is sealed by solidifying the low melting point solder 10. The solder injection port 4a is closed by the solidified low melting point solder 10.

  In step S7 of sealing the cylindrical portion 4 with the low melting point solder 10, the cylindrical portion 4 is heated mainly for melting the low melting point solder 10, but the inside of the case 1, particularly the optical element 5 and the optical fiber. The fixed portion 3 and the adhesive 9 are not heated excessively. For example, as shown in FIG. 1, the width of the case 1 made of Kovar is 13 mm, the depth is 21 mm, the height is 8 mm, the diameter of the cylindrical portion 4 is 3 mm, the length is 9 mm, and the sealing range by the low melting point solder 10 Can be fixed in the case 1 even if tin-bismuth eutectic solder is injected into the cylindrical portion 4 as the low melting point solder 10 and heated to 150 ° C. and melted. The temperature of the optical element 5 is kept below 100 ° C. Therefore, the adhesive 9 and the optical fiber 3 are not damaged or displaced.

  Further, after sealing with the low melting point solder 10, the adhesive 11 is injected and solidified from the adhesive injection port 4b, and the inside of the cylindrical portion 4 is also fixed by the adhesive 11 (step S8). As the adhesive 11, a silicon-based adhesive or an epoxy-based adhesive is used. The adhesive injection port 4 b is closed by the solidified adhesive 11.

  Next, the lid member 2 is placed on the opening 1a of the case 1 and joined by YAG laser welding (step S9). In the YAG laser welding apparatus used in the present embodiment, for example, as shown in FIG. 6, a laser emitting unit 14 incorporating a condenser lens 14a is connected from a YAG laser transmitter 12 through an optical fiber cord 13. And an XY table 15 on which a workpiece, that is, an optical device is mounted and movable. From this laser emitting unit 14, laser 19 is irradiated in a pulse shape toward the outer edge of the opening 1 a of the case 1 and the joint portion of the lid member 2 to be welded. As an example, as shown in FIG. 7, the spot size of the laser beam 19 is about 0.45 mm, the energy per pulse is 0.5 to 1 J, and the peak output is 0.5 to 1 kW. . Then, strong bonding with airtightness is ensured by irradiating the laser 19 in a pulsed manner while moving the case 1 and the lid member 2 by the XY table 15 so that adjacent melting spots overlap each other by 60 to 85%. Is done. The laser welding is preferably performed in a nitrogen atmosphere or while partially blowing nitrogen on the laser irradiation portion in a low humidity environment. The reason is to prevent oxidation and improve the molten state, and to keep the inside of the package after sealing in a low humidity state and prevent condensation.

  According to the present embodiment, even when the package shape of the optical device is complicated or the shape is changed, it can be easily handled by controlling the movement of the laser emitting unit 14 or the XY table 15 that operates the optical device. .

  As the optical fiber cord 13 of the YAG laser welding apparatus of this embodiment, either a GI (graded index) fiber or an SI (step index) fiber is selectively used. Since the SI fiber has a substantially uniform energy transfer distribution in the cross section, the melted portion is shallow and uniform. Therefore, when the thickness of the welded portion of the lid member 2 is 0.2 mm or less, it is better to use SI fiber. Further, the condensing lens 14a in the laser emission unit 14 may have a focal length set according to a required work distance W (see FIG. 6).

  The laser welding apparatus and method are not limited to the examples described above. For example, instead of moving the optical device, which is a workpiece, laser welding may be performed while moving the laser emitting unit 14 and welding may be performed. It is important that the laser emitting unit 14 and the optical device move relatively. The relative movement between the laser emitting unit 14 and the optical device may be continuous movement or intermittent movement. In the case of intermittent movement, pulsed laser irradiation and relative movement of the laser emitting unit 14 and the optical device may be performed alternately. In any case, it is set in consideration of the energy and irradiation time per pulse of the laser 19 and the speed of relative movement between the laser emitting unit 14 and the optical device. However, in the case of an optical device having a very complicated shape, there is a possibility that it is difficult to always make a relative movement at a constant speed. In such a case, it is considered that intermittent movement is preferable. Further, the laser emitting unit 14 and the optical device may be relatively moved while irradiating the laser 19 continuously instead of in a pulse form.

  Next, a second embodiment of the present invention will be described with reference to the drawings. In addition, about the part similar to 1st Embodiment, the same code | symbol is provided and description is abbreviate | omitted.

  In the present embodiment, as shown in FIG. 8, a multi-core optical fiber is used as the optical fiber 3, and the solder injection port 4a and the adhesive injection port 4b of the cylindrical portion 4 are horizontal rather than above the fiber alignment surface. In the position. According to this configuration, the low-melting-point solder can easily go up and down on the fiber alignment surface, and can be fixed more firmly and reliably. In FIG. 8, the low melting point solder 10 and the adhesive 11 are omitted for easy understanding.

(A) is the top view of the optical device of the 1st Embodiment of this invention which notched some lid members, (b) is the sectional view on the AA line. 1A is a cross-sectional view taken along the line B-B in FIG. 1 showing a state in which the arrangement of the optical fibers is disturbed, and FIG. 1B is a cross-sectional view taken along the line B-B in FIG. It is. (A) is a principal part enlarged plan view which shows the other example of the optical device shown in FIG. 1, (b) is the EE sectional view taken on the line. (A) is a principal part enlarged plan view which shows the further another example of the optical device shown in FIG. 1, (b) is the FF sectional view taken on the line. It is a flowchart which shows the manufacturing method of the optical device of the 1st Embodiment of this invention. It is a perspective view which shows roughly the YAG laser irradiation apparatus used with the manufacturing method of the optical device of the 1st Embodiment of this invention. It is a top view which shows roughly the laser pulse irradiated in the manufacturing method of the optical device of the 1st Embodiment of this invention. (A) is the top view which notched a part of cover member of the optical device of the 2nd Embodiment of this invention, (b) is the side view. It is explanatory drawing which shows the conventional can seal welding process. It is explanatory drawing which shows the conventional parallel seam welding process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Case 1a Opening part 1b Hole part 2 Cover member 3 Optical fiber 3a Metallized part 4 Cylindrical part 4a Solder injection port 4b Adhesive injection port 5 Optical element 6 Rubber hood 7 Support member 8 Drive unit 9 Adhesive 10 Low Melting point solder 11 Adhesive 12 YAG laser transmitter 13 Optical fiber cord 14a Condensing lens 14 Laser emitting unit 15 XY table 16 Unfilled portion 17 Substrate 17a V groove 18 Ferrule 19 Laser D Distance from the cylindrical portion to the outer edge of the opening W Work distance 101 Element 102 Cap 103 Stem 104, 105 Electrode 106 Roller electrode 107 Case 108 Lid member

Claims (27)

A hollow case having at least one opening;
A cylindrical portion protruding outside from a hole provided in a side surface of the case;
An optical fiber that penetrates through the tubular portion and the hole and extends from the inside of the case to the outside, and is fixed in the tubular portion by a low melting point solder that seals the tubular portion;
An optical device having a lid member joined to the case so as to close the opening by laser welding.   2. The optical device according to claim 1, wherein the cylindrical portion is separated from an outer edge of the opening of the case to at least an outside of a range where thermal energy is transmitted during laser welding for joining the lid member to the case. .   The said cylindrical part is separated from the outer edge of the said opening part of the said case by the distance longer than the penetration depth of the laser at the time of the laser welding for joining the said cover member to the said case at least. Optical devices.   The optical device according to claim 1, wherein the laser welding is YAG (Yttrium-Aluminum-Garnet) laser welding.   The optical device according to claim 1, further comprising an optical element arranged in the case so that the optical axis coincides with the optical fiber.   The optical device according to claim 1, wherein the lid member and the cylindrical portion are made of Kovar or 42 nickel-iron.   The optical device according to claim 1, wherein the case is made of any one of Kovar, 42 nickel-iron, and a ceramic material.   The portion sealed with the low melting point solder of the optical fiber is subjected to metallization treatment with nickel and gold in a state where the coating is removed. Optical device.   The optical device according to claim 8, wherein the thickness of the nickel layer formed by metallizing the optical fiber is 1 μm or less, and the thickness of the gold layer is 0.2 μm or less.   The optical device according to claim 8 or 9, wherein a length of the portion of the optical fiber that has been subjected to the metallization treatment in a state where the coating is removed is 2 mm to 5 mm.   The metallization process is performed only on a part of the optical fiber where the coating is removed, and the metallization process is performed on a part where the coating is removed and the metallization process is not performed. The optical device according to any one of claims 8 to 10, wherein a part of the front end side of the part is covered with a protective member.   The optical device according to claim 1, wherein a nickel plating layer having a thickness of 1 μm to 5 μm is formed on the case and the cylindrical part.   The optical device according to claim 1, wherein a gold plating layer having a thickness of 0.05 μm to 1 μm is formed on at least an inner surface of the cylindrical part. An optical fiber is connected to a hollow case having at least one opening, a hole provided on a side surface, and a cylindrical part protruding outward from the hole, and the cylindrical part and the hole. A step of extending through the case and extending from the inside of the case;
Sealing the cylindrical portion with a low melting point solder and fixing the optical fiber in the cylindrical portion;
And a step of joining a lid member to the case so as to close the opening by laser welding after sealing the cylindrical portion.   The manufacturing method of the optical device of Claim 14 including the process of attaching the said cylindrical part to the side surface of the said case before the process of arrange | positioning the said optical fiber. Placing the optical element in the case;
The method of manufacturing an optical device according to claim 14, further comprising a step of aligning the optical axes of the optical element and the end of the optical fiber and relatively fixing them.   The cylindrical portion is provided at a position away from an outer edge of the opening of the case to at least a range where thermal energy is transmitted by laser welding in a step of joining the lid member to the case. The manufacturing method of the optical device of any one.   The said cylindrical part is provided in the position away from the outer edge of the said opening part of the said case by the distance longer than the penetration depth of the laser by the laser welding of the process of joining at least the said cover member to the said case. The method for manufacturing an optical device according to any one of 16.   The method of manufacturing an optical device according to any one of claims 14 to 18, wherein the laser welding is YAG (Yttrium-Aluminum-Garnet) laser welding.   The method for manufacturing an optical device according to claim 14, wherein the lid member and the cylindrical portion are made of Kovar or 42 nickel-iron.   21. The method of manufacturing an optical device according to claim 14, wherein the case is made of any one of Kovar, 42 nickel-iron, and a ceramic material.   22. The method according to claim 14, further comprising a step of removing a coating in advance on a portion of the optical fiber that is sealed with the low-melting-point solder, and then performing a metallization process using nickel and gold. Optical device manufacturing method.   23. The method of manufacturing an optical device according to claim 22, wherein a nickel layer having a thickness of 1 [mu] m or less and a gold layer having a thickness of 0.2 [mu] m or less are formed in the step of metallizing the optical fiber.   The method for manufacturing an optical device according to claim 22 or 23, wherein the metallization treatment is performed in a range of 2 mm to 5 mm in length in the step of metallizing the optical fiber. In the step of performing the metallization process on the optical fiber, the metallization process is performed only on a part of the part from which the coating is removed,
25. The method according to any one of claims 22 to 24, further comprising a step of covering a part of the front end side of a portion where the coating is removed and the metallization process is not performed with respect to the metallization process with a protective member. The manufacturing method of the optical device of description.   The method for manufacturing an optical device according to any one of claims 14 to 25, further comprising a nickel plating step of forming a nickel plating layer having a thickness of 1 µm to 5 µm on the case and the cylindrical portion.   The method for manufacturing an optical device according to any one of claims 14 to 26, further comprising a gold plating step of forming a gold plating layer having a thickness of 0.05 µm to 1 µm on at least an inner surface of the cylindrical portion.

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